MacTeX - TeX Live Utility broken after 2015 update
You don't need to write to Herb for a fix. Credit goes to Bruno Voisin for finding the solution to this. Some background is here:
https://github.com/amaxwell/tlutility/issues/17#issuecomment-111517743
I think the simplest solution is here, requiring use of the Terminal:
http://tug.org/pipermail/tex-live/2015-June/036927.html
cd /tmp
curl 'https://www.tug.org/svn/texlive/trunk/Master/release-texlive.txt?revision=36787&view=co' > release-texlive.txt
sudo cp release-texlive.txt /usr/local/texlive/2015
Each of those three commands should be on a single line; the second is wrapped on this page. An updated version of MacTeX should be making its way around the CTAN mirrors right now.
Quoting the Tex on MacOSX Mailing list:
The version of TeX Live 2015 that was originally released in MacTeX-2015 is missing a file needed by TeX Live Utility so an updated version should be released in another day;
http://permalink.gmane.org/gmane.comp.tex.macosx/47095